Ibn Umar reported Allah's Messenger (ﷺ) as saying
When there are three (persons) , two should not converse secretly between themselves to the exclusion of the (third) one.
This hadith has been reported on the authority of lbn 'Umar through two different chains of transmitters.
'Abdullah reported Allah's Messenger (ﷺ) as saying
If you are three, two amongst you should not converse secretly between yourselves to the exclusion of the other (third one), unti some other people join him (and dispel his loneliness), for it may hurt his feelings.
'Abdullah reported Allah's Messenger (ﷺ) as saying
If you are three, two should not converse secretly to the exclusion of your companion for that hurts his feelings.
This hadith has been reported on the authority of A'mash with the same chain of transmitters.